/* ----------------------------------------------------------------------
 * Project:      CMSIS DSP Library
 * Title:        arm_cfft_f64.c
 * Description:  Combined Radix Decimation in Frequency CFFT Double Precision Floating point processing function
 *
 * $Date:        29. November 2019
 * $Revision:    V1.0.0
 *
 * Target Processor: Cortex-M cores
 * -------------------------------------------------------------------- */
/*
 * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the License); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an AS IS BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "arm_math.h"
#include "arm_common_tables.h"


extern void arm_radix4_butterfly_f64(
	float64_t *pSrc,
	uint16_t fftLen,
	const float64_t *pCoef,
	uint16_t twidCoefModifier);

extern void arm_bitreversal_64(
	uint64_t *pSrc,
	const uint16_t   bitRevLen,
	const uint16_t *pBitRevTable);

/**
* @} end of ComplexFFT group
*/

/* ----------------------------------------------------------------------
 * Internal helper function used by the FFTs
 * ---------------------------------------------------------------------- */

/*
* @brief  Core function for the Double Precision floating-point CFFT butterfly process.
* @param[in, out] *pSrc            points to the in-place buffer of F64 data type.
* @param[in]      fftLen           length of the FFT.
* @param[in]      *pCoef           points to the twiddle coefficient buffer.
* @param[in]      twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
* @return none.
*/

void arm_radix4_butterfly_f64(
	float64_t *pSrc,
	uint16_t fftLen,
	const float64_t *pCoef,
	uint16_t twidCoefModifier)
{

	float64_t co1, co2, co3, si1, si2, si3;
	uint32_t ia1, ia2, ia3;
	uint32_t i0, i1, i2, i3;
	uint32_t n1, n2, j, k;

	float64_t t1, t2, r1, r2, s1, s2;


	/*  Initializations for the fft calculation */
	n2 = fftLen;
	n1 = n2;
	for (k = fftLen; k > 1U; k >>= 2U) {
		/*  Initializations for the fft calculation */
		n1 = n2;
		n2 >>= 2U;
		ia1 = 0U;

		/*  FFT Calculation */
		j = 0;
		do {
			/*  index calculation for the coefficients */
			ia2 = ia1 + ia1;
			ia3 = ia2 + ia1;
			co1 = pCoef[ia1 * 2U];
			si1 = pCoef[(ia1 * 2U) + 1U];
			co2 = pCoef[ia2 * 2U];
			si2 = pCoef[(ia2 * 2U) + 1U];
			co3 = pCoef[ia3 * 2U];
			si3 = pCoef[(ia3 * 2U) + 1U];

			/*  Twiddle coefficients index modifier */
			ia1 = ia1 + twidCoefModifier;

			i0 = j;
			do {
				/*  index calculation for the input as, */
				/*  pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */
				i1 = i0 + n2;
				i2 = i1 + n2;
				i3 = i2 + n2;

				/* xa + xc */
				r1 = pSrc[(2U * i0)] + pSrc[(2U * i2)];

				/* xa - xc */
				r2 = pSrc[(2U * i0)] - pSrc[(2U * i2)];

				/* ya + yc */
				s1 = pSrc[(2U * i0) + 1U] + pSrc[(2U * i2) + 1U];

				/* ya - yc */
				s2 = pSrc[(2U * i0) + 1U] - pSrc[(2U * i2) + 1U];

				/* xb + xd */
				t1 = pSrc[2U * i1] + pSrc[2U * i3];

				/* xa' = xa + xb + xc + xd */
				pSrc[2U * i0] = r1 + t1;

				/* xa + xc -(xb + xd) */
				r1 = r1 - t1;

				/* yb + yd */
				t2 = pSrc[(2U * i1) + 1U] + pSrc[(2U * i3) + 1U];

				/* ya' = ya + yb + yc + yd */
				pSrc[(2U * i0) + 1U] = s1 + t2;

				/* (ya + yc) - (yb + yd) */
				s1 = s1 - t2;

				/* (yb - yd) */
				t1 = pSrc[(2U * i1) + 1U] - pSrc[(2U * i3) + 1U];

				/* (xb - xd) */
				t2 = pSrc[2U * i1] - pSrc[2U * i3];

				/* xc' = (xa-xb+xc-xd)co2 + (ya-yb+yc-yd)(si2) */
				pSrc[2U * i1] = (r1 * co2) + (s1 * si2);

				/* yc' = (ya-yb+yc-yd)co2 - (xa-xb+xc-xd)(si2) */
				pSrc[(2U * i1) + 1U] = (s1 * co2) - (r1 * si2);

				/* (xa - xc) + (yb - yd) */
				r1 = r2 + t1;

				/* (xa - xc) - (yb - yd) */
				r2 = r2 - t1;

				/* (ya - yc) -  (xb - xd) */
				s1 = s2 - t2;

				/* (ya - yc) +  (xb - xd) */
				s2 = s2 + t2;

				/* xb' = (xa+yb-xc-yd)co1 + (ya-xb-yc+xd)(si1) */
				pSrc[2U * i2] = (r1 * co1) + (s1 * si1);

				/* yb' = (ya-xb-yc+xd)co1 - (xa+yb-xc-yd)(si1) */
				pSrc[(2U * i2) + 1U] = (s1 * co1) - (r1 * si1);

				/* xd' = (xa-yb-xc+yd)co3 + (ya+xb-yc-xd)(si3) */
				pSrc[2U * i3] = (r2 * co3) + (s2 * si3);

				/* yd' = (ya+xb-yc-xd)co3 - (xa-yb-xc+yd)(si3) */
				pSrc[(2U * i3) + 1U] = (s2 * co3) - (r2 * si3);

				i0 += n1;
			} while (i0 < fftLen);
			j++;
		} while (j <= (n2 - 1U));
		twidCoefModifier <<= 2U;
	}
}

/*
* @brief  Core function for the Double Precision floating-point CFFT butterfly process.
* @param[in, out] *pSrc            points to the in-place buffer of F64 data type.
* @param[in]      fftLen           length of the FFT.
* @param[in]      *pCoef           points to the twiddle coefficient buffer.
* @param[in]      twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.
* @return none.
*/

void arm_cfft_radix4by2_f64(
	float64_t *pSrc,
	uint32_t fftLen,
	const float64_t *pCoef)
{
	uint32_t i, l;
	uint32_t n2, ia;
	float64_t xt, yt, cosVal, sinVal;
	float64_t p0, p1, p2, p3, a0, a1;

	n2 = fftLen >> 1;
	ia = 0;
	for (i = 0; i < n2; i++) {
		cosVal = pCoef[2 * ia];
		sinVal = pCoef[2 * ia + 1];
		ia++;

		l = i + n2;

		/*  Butterfly implementation */
		a0 = pSrc[2 * i] + pSrc[2 * l];
		xt = pSrc[2 * i] - pSrc[2 * l];

		yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
		a1 = pSrc[2 * l + 1] + pSrc[2 * i + 1];

		p0 = xt * cosVal;
		p1 = yt * sinVal;
		p2 = yt * cosVal;
		p3 = xt * sinVal;

		pSrc[2 * i]     = a0;
		pSrc[2 * i + 1] = a1;

		pSrc[2 * l]     = p0 + p1;
		pSrc[2 * l + 1] = p2 - p3;

	}

	// first col
	arm_radix4_butterfly_f64(pSrc, n2, (float64_t *)pCoef, 2U);
	// second col
	arm_radix4_butterfly_f64(pSrc + fftLen, n2, (float64_t *)pCoef, 2U);

}

/**
  @addtogroup ComplexFFT
  @{
 */

/**
  @brief         Processing function for the Double Precision floating-point complex FFT.
  @param[in]     S              points to an instance of the Double Precision floating-point CFFT structure
  @param[in,out] p1             points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place
  @param[in]     ifftFlag       flag that selects transform direction
                   - value = 0: forward transform
                   - value = 1: inverse transform
  @param[in]     bitReverseFlag flag that enables / disables bit reversal of output
                   - value = 0: disables bit reversal of output
                   - value = 1: enables bit reversal of output
  @return        none
 */

void arm_cfft_f64(
	const arm_cfft_instance_f64 *S,
	float64_t *p1,
	uint8_t ifftFlag,
	uint8_t bitReverseFlag)
{
	uint32_t  L = S->fftLen, l;
	float64_t invL, * pSrc;

	if (ifftFlag == 1U) {
		/*  Conjugate input data  */
		pSrc = p1 + 1;
		for (l = 0; l < L; l++) {
			*pSrc = -*pSrc;
			pSrc += 2;
		}
	}

	switch (L) {
	case 16:
	case 64:
	case 256:
	case 1024:
	case 4096:
		arm_radix4_butterfly_f64(p1, L, (float64_t *)S->pTwiddle, 1U);
		break;

	case 32:
	case 128:
	case 512:
	case 2048:
		arm_cfft_radix4by2_f64(p1, L, (float64_t *)S->pTwiddle);
		break;

	}

	if (bitReverseFlag) {
		arm_bitreversal_64((uint64_t *)p1, S->bitRevLength, S->pBitRevTable);
	}

	if (ifftFlag == 1U) {
		invL = 1.0 / (float64_t)L;
		/*  Conjugate and scale output data */
		pSrc = p1;
		for (l = 0; l < L; l++) {
			*pSrc++ *=   invL ;
			*pSrc  = -(*pSrc) * invL;
			pSrc++;
		}
	}
}

/**
  @} end of ComplexFFT group
 */
